Additional Study Information: We are recruiting volunteers, aged 18-70 without diabetes, for a research study on determining how much of the blood sugar- lowering hormone insulin the body can produce in order to better identify people at risk for diabetes in the future. To do this, we will have approximately 15 participants stay for approximately 30 hours (including overnight) in the hospital. On the morning first day, we will measure how much insulin the body produces in response to glucose (sugar) infused intravenously (into the vein) over 2 hours. That evening, we will give a single dose of a medication called alpelisib (brand name: Piqray), which is a drug (pill) used to treat certain breast cancers and temporarily makes the body resistant to the actions of insulin. We expect that the body will then have to produce a high amount of insulin to overcome alpelisib's interference, and so we will measure that insulin production on the morning of the second study day during a mixed meal tolerance test, where participants drink a liquid nutritional supplement and have blood drawn at intervals for 4 hours. Eligible participants will receive compensation for their participation, including a stipend (salary) of $500 and reimbursement for travel expenses.